This invention pertains to a vertical vessel unheading device and its associated support structure. It pertains particularly to such an unheading device for the lower flange and head assembly of a coking vessel, which device is movably supported directly from the vessel support structure by multiple elongated extendable actuators each pivotably attached to such support structure and the device is arranged for periodic removal and replacement during vessel operations.
Unheading devices provided at the lower end of large coking drums or vessels used in petroleum refinery operations and which are capable of remote operation are known, such as disclosed by U.S. Pat. No. 4,726,109 to Malsbury et al and U.S. Pat. No. 4,960,358 to DiGiacomo et al. In past installations of such remotely operated unheading devices for coking vessels, the unheading device has been supported by four vertically oriented actuator cylinders pivotably attached to trunnions welded onto the coking vessel bottom cone section. However, these welded attachments require regularly scheduled inspection and testing to ensure desired load capacity of the attachment welds. Because any needed repairs could require undesired post weld heat treatment locally at the attachment welds and extending undesired vessel shutdowns, an improved unheader device support arrangement for such vertically-oriented actuator cylinders for such unheading devices is needed.